Animal proteins derived from tissues remaining after meat packing operations have been a source of useful protein preparations for many years. Collagen or gelatin proteins have been extracted from animal tissues and have been used historically in the preparation of animal glues, food gelatins and other protein based products. Collagen or gelatin preparations typically take the form of a particulate or powdered material. The gelatin powder is often sold in combination with other powdered ingredients that add unique properties or provide new utilities to the preparation.
An animal tissue source or mixtures of such sources are commonly extracted using a heated aqueous mixture. Aqueous mixture forms a solution of the collagen or protein. Such solutions are often dried to form the well known collagen or gelatin powdered material. When used, the gelatin powder is combined with water to reconstitute the hydrated protein. This common hydration-dehydration-hydration processing sequence for forming the gelatin powder and reconstituting gelatin powder into a gelatin aqueous gel has a substantial energy drawback.
In order to convert an aqueous protein extract into a solid particulate material, a substantial amount of heat energy is applied removing water from the aqueous protein composition. The removal of water results in a solid proteinaceous material having about 13 wt % water, or somewhat less, in common gelatin powdered products. The protein solids can then be processed into a finely divided particulate (typically less than 20 U.S. mesh or less than about 0.8 mm or 800 .mu.m) which is then packaged and distributed to end users. An end user taking the particulate protein, typically combines the material with a major proportion of water and, using heat and agitation, rehydrates the protein resulting in a useful material that can be further diluted or combined with other ingredients as necessary. Such typical labor and energy intensive processing steps are well known and have been common for many years.
General gelatin extraction processing is disclosed in Donnelly et al., U.S. Pat. No. 4,043,996; Petersen et al., U.S. Pat. No. 4,064,008; Oudem, U.S. Pat. No. 4,176,117; Muller, U.S. Pat. No. 4,889,920 (which teaches a powdered gelatin having a water content between 8 and 13%); and Moy et al., U.S. Pat. No. 5,459,241. Processes using a caustic pH or an acid pH or both in processing gelatin are disclosed in, for example, Consolazio et al., U.S. Pat. No. 4,374,063 and Nasrallah et al., U.S. Pat. No. 5,210,182. Gelatin derived from a bone or skin source is disclosed in Wojcik, U.S. Pat. No. 4,232,425; Vollmer et al., U.S. Pat. No. 4,402,873; England et al., U.S. Pat. No. 4,427,583; and Grossman et al., U.S. Pat. No. 5,093,474. Processing of a gelatin and glycerol recycled product is shown in Schmidt et al., U.S. Pat. No. 5,288,408. An oxidative process for maintaining the methionine content is shown in Wrathall et al., U.S. Pat. No. 5,412,075. Nishibori, U.S. Pat. No. 5,080,292 teaches a powdered gelatin particulate material. Graesser et al., U.S. Pat. No. 4,369,069 disclose a powdered gelatin product having a desirable content of alpha-gelatin. A gelatin granule or powder having 1-13 wt % water is disclosed in Koepff et al., U.S. Pat. No. 4,992,100. The use of gelatin for binding various types of agglomerates or structures is shown in Cummisford et al., U.S. Pat. No. 4,098,859; Ueda et al., U.S. Pat. No. 4,957,558; Siak et al., U.S. Pat. No. 5,320,157; and Moore et al., U.S. Pat. No. 5,262,100. Berta, U.S. Pat. Nos. 4,867,983 and 4,921,108 teach apparatus and methods for forming GELCAPS.RTM. comprising a medication formed in a gelatin encapsulate coating.
One historical use of substantial quantities of collage or gelatin protein is in the form of an animal glue. The use of such a glue was first recorded in about 4000 B.C. Throughout subsequent centuries, glue and crude gelatin extracts with poor organoleptic properties were prepared by boiling bone and hide pieces in a lime solution to cool and gel. Late in the seventeenth century, the first commercial gelatin manufacturing began. At the beginning of the nineteenth century, commercial production methods gradually were improved to achieve the manufacture of high molecular weight collagen extracts with good quality that form characteristic gelatin gels. Animal glues are the hydrolysis product of collagen or gelatin. Such a hydrolysis product is an amorphous collection of protein fragments. One glue precursor is sold in the form of a finely divided solid product comprising a protein powder, containing 11-13 wt % water with certain animal glue additives. When used, the powder is typically diluted with water and combined with additives or agents that exert a control or a change in effect of the gelling properties of the glue. Such agents are commonly used to control gelation and to increase the rate of gelation but not the rigidity of the final gel. Citrates, tartrates and maleates are often used in these animal glue preparations. Typically the amount of gelatin in the final aqueous animal glue preparation is less than 10 wt % of protein on the aqueous glue composition.
Gelatin proteins are also used in food grade flavored gelatin preparations. A food grade flavored gelatin preparation is commonly sold in the form of a powder containing sugar or other sweeteners, preservatives, flavors, dyes, an amount of powdered gelatin (about 5 to 15 wt % based on the gelatin preparation) and a polycarboxylic acid composition used to add both a tart taste and to help in gel formation, etc. The powdered gelatin material is combined with hot water to form a wet gelatin food having a protein content of less than about 5 wt % based on the gelatin food.
The use of gelatin can be based on the combination of properties exhibited by good quality protein. Such properties include reversible gel to sol transition of aqueous solution; a useful range of viscosity of warm aqueous solutions; ability to act as a protective colloid; gel films water permeability; and substantial insolubility in cold water, but complete solubility in hot water. These properties are utilized in food, pharmaceutical, photographic casting and other varied industries. Further, gelatin can form a strong, uniform, clear, moderately flexible coating which can swell and absorb water. Such films can be ideal for the manufacture of photographic articles and pharmaceutical capsules and caplets.
The typical powdered collagen or gelatin product comprising a powdered product, having 13% or less water can be difficult to work and can require substantial energy input for both manufacturing and rehydration. A substantial need exists to improve the composition of the gelatin product to make its use in a variety of industrial processes less energy intensive and more easily accomplished.